TY - JOUR
T1 - Three distinct chromatin domains in telomere ends of polytene chromosomes in Drosophila melanogaster Tel mutants
AU - Andreyeva, Evgenia N.
AU - Belyaeva, Elena S.
AU - Sameshin, Valerii F.
AU - Pokholkova, Galina V.
AU - Zhimulev, Igor F.
PY - 2005/12/1
Y1 - 2005/12/1
N2 - Drosophila melanogaster telomeric DNA is known to comprise two domains: the terminal tract of retrotransposons (HeT-A, TART and TAHRE) and telomere-associated sequences (TAS). Chromosome tips are capped by a protein complex, which is assembled on the chromosome ends independently of the underlying terminal DNA sequences. To investigate the properties of these domains in salivary gland polytene chromosomes, we made use of Tel mutants. Telomeres in this background are elongated owing to the amplification of a block of terminal retroelements. Supercompact heterochromatin is absent from the telomeres of polytene chromosomes: electron microscopy analysis identifies the telomeric cap and the tract of retroelements as a reticular material, having no discernible banding pattern, whereas TAS repeats appear as faint bands. According to the pattern of bound proteins, the cap, tract of retroelements and TAS constitute distinct and non-overlapping domains in telomeres. SUUR, HP2, SU(VAR)3-7 and H3Me3K27 localize to the cap region, as has been demonstrated for HP1. All these proteins are also found in pericentric heterochromatin. The tract of retroelements is associated with proteins characteristic for both heterochromatin (H3Me3K9) and euchromatin (H3Me3K4, JIL-1, Z4). The TAS region is enriched for H3Me3K27. PC and E(Z) are detected both in TAS and many intercalary heterochromatin regions. Telomeres complete replication earlier than heterochromatic regions. The frequency of telomeric associations in salivary gland polytene chromosomes does not depend on the SuUR gene dosage, rather it appears to be defined by the telomere length.
AB - Drosophila melanogaster telomeric DNA is known to comprise two domains: the terminal tract of retrotransposons (HeT-A, TART and TAHRE) and telomere-associated sequences (TAS). Chromosome tips are capped by a protein complex, which is assembled on the chromosome ends independently of the underlying terminal DNA sequences. To investigate the properties of these domains in salivary gland polytene chromosomes, we made use of Tel mutants. Telomeres in this background are elongated owing to the amplification of a block of terminal retroelements. Supercompact heterochromatin is absent from the telomeres of polytene chromosomes: electron microscopy analysis identifies the telomeric cap and the tract of retroelements as a reticular material, having no discernible banding pattern, whereas TAS repeats appear as faint bands. According to the pattern of bound proteins, the cap, tract of retroelements and TAS constitute distinct and non-overlapping domains in telomeres. SUUR, HP2, SU(VAR)3-7 and H3Me3K27 localize to the cap region, as has been demonstrated for HP1. All these proteins are also found in pericentric heterochromatin. The tract of retroelements is associated with proteins characteristic for both heterochromatin (H3Me3K9) and euchromatin (H3Me3K4, JIL-1, Z4). The TAS region is enriched for H3Me3K27. PC and E(Z) are detected both in TAS and many intercalary heterochromatin regions. Telomeres complete replication earlier than heterochromatic regions. The frequency of telomeric associations in salivary gland polytene chromosomes does not depend on the SuUR gene dosage, rather it appears to be defined by the telomere length.
KW - Drosophila
KW - Heterochromatin
KW - Silencing
KW - Telomeres
KW - Telomeric Associations
UR - http://www.scopus.com/inward/record.url?scp=30544432864&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=30544432864&partnerID=8YFLogxK
U2 - 10.1242/jcs.02654
DO - 10.1242/jcs.02654
M3 - Article
C2 - 16278293
AN - SCOPUS:30544432864
SN - 0021-9533
VL - 118
SP - 5465
EP - 5477
JO - Journal of cell science
JF - Journal of cell science
IS - 23
ER -